Found these page very useful in my regular expression fun:

• Information - http://www.regular-expressions.info
• Validator - http://www.sweeting.org/mark/html/revalid.php

I get rusty so quick because I do not get to use regex's, perl, and various scripting languages with a consistent enough frequency.  I know how I want to do it in my head, know it is possible, but can never remeber the syntax.  Also found the RegEx validator super handy when trying to get things working.